Production & Technology

Towards the end of the 17th century, the Thalsaline still extracted its salt almost as in the Middle Ages. The earliest illustrated description of it comes from Georg Agricola's (1494-1555) famous mining manual De re metallica. The precise explanations and woodcuts suggest that the Saxon physician and polymath probably knew Halle's saltworks from his own experience.

The salt was produced in the salt huts. These were simple half-timbered houses made of fir or spruce wood, straw and clay. Each hut had a large dug-in barrel, half of which stood in the alley and half in the house. So the brine could be poured in from the outside and taken out from the inside.

The model of a large salt hut from around 1700 is one of the few historical testimonies that can still give us a vivid impression of the old boiling huts on the Thalsaline. It was probably made as a teaching model for visual instrution in the orphanage schools. It was used to illustrate the typical construction of the salt huts and the traditional salt boiling process. The model is mentioned for the first time in the catalogue of the Cabinet of Artefacts and Natural Curiosities, which was newly established in 1741 and where it is still exhibited today.

The year of construction and builder of the model are not yet known. The still preserved equipment corresponds to a simple, wood-fired boiling hut of the 16th and 17th centuries. However, the remains of a pump in the brine barrel indicate that the model could have been built in 1699 at the earliest, when such pumps became common.

Is the detailed model possibly a replica of a very specific salt boiling hut? The house sign painted on the facade – a duck – at least suggests so, because a boiling hut called »Duckbird« actually existed. It is marked on the plan of the Thalsaline from 1746, in the middle of today's place called »Hallmarkt«. Even its ground plan and the location of the brine barrel match the model.

Like iron smelting and glass production, salt boiling also consumed vast quantities of firewood, which seemed to be becoming increasingly scarce. Therefore, resourceful minds were already trying to reduce consumption at the end of the 16th century by means of new boiling techniques. In Halle, too, tinkerers and »project makers« experimented with wood-saving boiling hearths and alternative fuels, which was expensive but led nowhere. For fear of financial losses, many Pfänners later distrusted any promises of innovation and preferred to stick to the tried and tested method.

The Brandenburg Elector wanted to have high-quality salt produced in his boiling huts on a large scale, but as cheaply as possible. The cheap fuel was to be hard coal from his own mines in Wettin and Löbejün northwest of Halle, which could also be transported upstream on the Saale river to Halle. But the coal burned badly in the conventional boiling cookers and the smoke made the salt black and bitter. So the boiling technology had to be renewed from the ground up.

With the new method, Bötticher succeeded in boiling impeccable salt that could rival that from Lüneburg. As a reward, he was appointed chief boiling master of the royal salt production.

By 1701, all of the sovereign's boiling huts had been modernised in Bötticher's style. Not so with the Pfänners. Only a few were open to the new process and modernised their technology. It was not until the middle of the 18th century that all the Pfännerschaft's boiling huts were heated with hard coal.

The small teaching model of a salt hut from the Cabinet of Artefacts and Natural Curiosities of the Francke Foundations features all of Bötticher's innovations in a simple form. It thus corresponds to the current state of boiling technology of the time and represents the important experimental phase of Prussian salt production. It was made by the Halle pastor, educator and inventor Christoph Semler (1669–1740). In 1708 he opened a Mathematical and Mechanical School in Halle for prospective apprentices of the craft – the first »Realschule«, a school for visual instruction, in Germany. There, a teacher taught technical correlations primarily using models that Semler made especially for this purpose.

The teaching material on the salt boiling hut not only explained its most important components on the model, but also conveyed solid basic knowledge about the salt boiling craft on the Thalsaline.